mempool: make max_tx_bytes configurable instead of max_msg_bytes (#3877)

Fix #3868 (comment)

Commits:

* mempool: make `max_tx_bytes` configurable instead of `max_msg_bytes`

* update CHANGELOG_PENDING

* apply suggestions from code review

mempool/clist_mempool.go

@@ -232,8 +232,8 @@ func (mem *CListMempool) CheckTxWithInfo(tx types.Tx, cb func(*abci.Response), t
 	// The size of the corresponding amino-encoded TxMessage
 	// can't be larger than the maxMsgSize, otherwise we can't
 	// relay it to peers.
-	if max := calcMaxTxSize(mem.config.MaxMsgBytes); txSize > max {
-		return ErrTxTooLarge{max, txSize}
+	if txSize > mem.config.MaxTxBytes {
+		return ErrTxTooLarge{mem.config.MaxTxBytes, txSize}
 	}
 
 	if mem.preCheck != nil {

mempool/clist_mempool_test.go

@@ -426,8 +426,8 @@ func TestMempoolMaxMsgSize(t *testing.T) {
 	mempl, cleanup := newMempoolWithApp(cc)
 	defer cleanup()
 
-	maxMsgSize := mempl.config.MaxMsgBytes
-	maxTxSize := calcMaxTxSize(mempl.config.MaxMsgBytes)
+	maxTxSize := mempl.config.MaxTxBytes
+	maxMsgSize := calcMaxMsgSize(maxTxSize)
 
 	testCases := []struct {
 		len int

mempool/reactor.go

@@ -263,8 +263,9 @@ func RegisterMempoolMessages(cdc *amino.Codec) {
 }
 
 func (memR *Reactor) decodeMsg(bz []byte) (msg MempoolMessage, err error) {
-	if l := len(bz); l > memR.config.MaxMsgBytes {
-		return msg, ErrTxTooLarge{memR.config.MaxMsgBytes, l}
+	maxMsgSize := calcMaxMsgSize(memR.config.MaxTxBytes)
+	if l := len(bz); l > maxMsgSize {
+		return msg, ErrTxTooLarge{maxMsgSize, l}
 	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
@@ -282,8 +283,8 @@ func (m *TxMessage) String() string {
 	return fmt.Sprintf("[TxMessage %v]", m.Tx)
 }
 
-// calcMaxTxSize returns the max size of Tx
+// calcMaxMsgSize returns the max size of TxMessage
 // account for amino overhead of TxMessage
-func calcMaxTxSize(maxMsgSize int) int {
-	return maxMsgSize - aminoOverheadForTxMessage
+func calcMaxMsgSize(maxTxSize int) int {
+	return maxTxSize + aminoOverheadForTxMessage
 }